1. Technical Field
The invention relates to air springs, and in particular to air springs for vehicles which have a vibration absorbing assembly incorporated therein to isolate the air spring sleeve vibrations from the adjacent end member and vehicle.
2. Background Information
Air springs typically include two end members which are sealingly connected to respective ends of a hollow fabric reinforced elastomeric sleeve. These air springs are used primarily for implementation in motor vehicles for supporting the vehicle body or for use in other types of equipment subject to shock to provide cushioning therefor. The air springs are sealed at the ends to form a pressurized fluid chamber within the sleeve. The air spring will generate a certain load at a given height and pressure, and upon the spring experiencing a road displacement input, the sleeve will begin to compress or extend as the end members move toward and away from each other respectively, to provide predictable dynamic load characteristics. Sudden movement of one end of the air spring will cause vibration of the; elastomeric sleeve which is transmitted from the sleeve to the end members and to the vehicle structure affecting the ride characteristics of the vehicle and suspension system.
Various types of vibration isolation have been devised to reduce or prevent the transmission of the sleeve vibrations to the end members and connected vehicle components. Certain of these vibration isolators use various types of elastomeric materials located at the end of the air spring where it is sealed to the end member, such as shown in U.S. Pat. Nos. 4,697,797 and 6,123,325. Other types use bearings and elastomeric materials at the connection of end cap or end members to the supporting vehicle structure, as shown in U.S. Pat. No. 5,690,319. Other types of air spring vibration isolation methods and apparatus use an elastomeric isolator which is mounted on the sleeve in such a manner to require additional sealed connections of the sleeve and vibration isolator, thus creating a potential leak path past the air sleeve from the interior pressure chamber. It is always desirable to reduce to a minimum the number of possible air leak paths from the internal fluid chamber of the air spring to the surrounding atmosphere.
Thus it is desirable to provide an air spring with vibration isolation which does not create a potential additional leak path from the internal fluid chamber to the surrounding atmosphere, yet which is usable with existing air spring constructions without increasing the effective height and size of the air spring, and which can be accomplished in a relatively simple and economical manner.
What the art needs is an air spring assembly which allows for control of the vibrations generated within or transmitted through the air spring sleeve from reaching the end members and vehicle structure without significantly changing the physical size and operating characteristics of the air spring.
The air spring of the present invention uses an elastomeric vibration isolator which is clamped to the air spring sleeve at a spaced distance from one of the end members by a rigid annular ring-like member located within the fluid chamber of the air spring sleeve which ring-like member sandwiches and clamps a portion of the sleeve to an outer rigid member. The sleeve is supported by this device, reducing sleeve tension and vibration transmission to the upper end closure by the air spring. This rigid outer member is isolated either from the end member by an elastomeric vibration isolator or from the sleeve with an elastomeric isolator, either of which will attenuate the transmission of the sleeve vibrations to the end member.
A further feature of the invention is to provide a mounting arrangement for a vibration isolator on the air spring sleeve without piercing or harming the sleeve and creating a potential air leak path between the internal pressure chamber and surrounding atmosphere.
Another aspect of the invention is to enable the vibration isolator to be mounted externally of the air spring and clamped to the sleeve and used in conjunction with a rigid restraining cylinder which extends along the air sleeve to reduce the outward radial expansion of the sleeve, and which protects the sleeve from the surrounding environment.
The internal rigid member, which mounts the elastomeric isolator in position, may have an outwardly curved surface to form a convolution in the air spring to assist its movement between compressed and expanded positions and to prevent pinching of the sleeve between the isolator components.